Just so you know, I tried your updated code and it ran successfully producing the below structure on my local hard drive (part listing). So perhaps your problem lies elsewhere, maybe with the firewall you mention. 
PowerEdge R610
    BIOS
        Windows Server 2008 x86
        BIOS
            OS Independent
                2009-03-30 - R610-010004BIOS.txt
                2009-05-27 - R610-010104BIOS.txt
                2009-08-31 - R610-010206BIOS.txt
                2009-12-14 - R610-010306BIOS.txt
                2010-04-15 - R610-020013BIOS.txt
                ...
    Chipset
        Driver
            Windows Server 2003
            Windows Server 2003 x64
            Windows Server 2008 R2
            Windows Server 2008 x64

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In reply to Re: Net::FTP::Recursive problems, prematurely closing connection by tangent
in thread Net::FTP::Recursive problems, prematurely closing connection by bowei_99

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